Spacer ring for disk drive spindle with load/unload feature, latch feature, and tribological overcoat

ABSTRACT

A hard disk drive utilizes a spacer ring at its inner diameter to load and unload the read/write heads. During relatively small shock events, the actuator is retained relative to the disk through a circumferential groove in the spacer ring. A complementary protrusion on the load/unload tab extends from the actuator into the groove to complete the retention. A tribological coating on the spacer ring and/or protrusion significantly reduces wear therebetween. However, during large shock events an inertial latch is used by the system to hold the actuator in place.

BACKGROUND OF THE INVENTION

[0001] 1. Technical Field

[0002] The present invention relates in general to an improved hard diskdrive, and in particular to an improved spacer ring for a disk drivehaving an inner diameter load/unload latching device.

[0003] 2. Description of the Prior Art

[0004] Generally, a data access and storage system consists of one ormore storage devices that store data on magnetic or optical storagemedia. For example, a magnetic storage device is known as a directaccess storage device (DASD) or a hard disk drive (HDD) and includes oneor more disks and a disk controller to manage local operationsconcerning the disks. The hard disks themselves are usually made ofaluminum alloy or a mixture of glass and ceramic, and are covered with amagnetic coating. Typically, two or three disks are stacked verticallyon a common spindle that is turned by a disk drive motor at severalthousand revolutions per minute (rpm).

[0005] The only other moving part within a typical HDD is the actuatorassembly. The actuator moves magnetic read/write heads to the desiredlocation on the rotating disk so as to write information to or read datafrom that location. Within most HDDs, the magnetic read/write head ismounted on a slider. A slider generally serves to mechanically supportthe head and any electrical connections between the head and the rest ofthe disk drive system. The slider is aerodynamically shaped to glideover moving air in order to maintain a uniform distance from the surfaceof the rotating disk, thereby preventing the head from undesirablycontacting the disk.

[0006] Typically, a slider is formed with an aerodynamic pattern ofprotrusions on its air bearing surface (ABS) that enables the slider tofly at a constant height close to the disk during operation of the diskdrive. A slider is associated with each side of each platter and fliesjust over the platter's surface. Each slider is mounted on a suspensionto form a head gimbal assembly (HGA). The HGA is then attached to asemi-rigid actuator arm that supports the entire head flying unit.Several semi-rigid arms may be combined to form a single movable unithaving either a linear bearing or a rotary pivotal bearing system.

[0007] The head and arm assembly is linearly or pivotally movedutilizing a magnet/coil structure that is often called a voice coilmotor (VCM). The stator of a VCM is mounted to a base plate or castingon which the spindle is also mounted. The base casting with its spindle,actuator VCM, and internal filtration system is then enclosed with acover and seal assembly to ensure that no contaminants can enter andadversely affect the reliability of the slider flying over the disk.When current is fed to the motor, the VCM develops force or torque thatis substantially proportional to the applied current. The armacceleration is therefore substantially proportional to the magnitude ofthe current. As the read/write head approaches a desired track, areverse polarity signal is applied to the actuator, causing the signalto act as a brake, and ideally causing the read/write head to stopdirectly over the desired track.

[0008] It is not uncommon for hard disk drives to experience some levelof mechanical shock events. For this reason, prior art drives arecommonly equipped with means for loading and unloading the read/writeheads on the actuator with respect to the disks. The load/unload devicesor ramps are typically located beyond the outer diameter of the disks inorder to protect the surfaces of the heads and the disks. Although thesedesigns are workable, an improved system and method for retaining theactuator and heads during shock events would be desirable.

SUMMARY OF THE INVENTION

[0009] One embodiment of a hard disk drive utilizes a spacer ring at itsinner diameter to load and unload the read/write heads of the drive withrespect to the disks. During relatively small shock events, the actuatoris retained relative to the disk through a circumferential groovelocated in the spacer ring. A complementary protrusion on theload/unload tab extends from the actuator into the groove to completethe retention. A tribological coating on the spacer ring and/orprotrusion significantly reduces wear and extends the life of theircontacting portions. However, during large shock events an inertiallatch is used by the system to hold the actuator in place.

[0010] The foregoing and other objects and advantages of the presentinvention will be apparent to those skilled in the art, in view of thefollowing detailed description of the preferred embodiment of thepresent invention, taken in conjunction with the appended claims and theaccompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0011] So that the manner in which the features, advantages and objectsof the invention, as well as others which will become apparent, areattained and can be understood in more detail, more particulardescription of the invention briefly summarized above maybe had byreference to the embodiment thereof which is illustrated in the appendeddrawings, which drawings form a part of this specification. It is to benoted, however, that the drawings illustrate only a preferred embodimentof the invention and is therefore not to be considered limiting of itsscope as the invention may admit to other equally effective embodiments.

[0012]FIG. 1 is a plan view of one embodiment of a disk driveconstructed in accordance with the present invention.

[0013]FIG. 2 is a sectional side view of a portion of the disk drive ofFIG. 1 taken along the line 2-2 of FIG. 1.

[0014]FIG. 3 is the sectional side view of FIG. 2 showing the actuatorarm in an engaged position relative to the spacer ring.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT OF THE PRESENTINVENTION

[0015] Referring to FIG. 1, a schematic drawing of one embodiment of aninformation storage system comprising a magnetic hard disk file or drive111 for a computer system is shown. Drive 111 has an outer housing orbase 113 containing a plurality of stacked, parallel magnetic disks 115(one shown) which are closely spaced apart. Disks 115 are rotated by aspindle motor assembly 131 having a central drive hub 117. An actuator121 comprises a plurality of parallel actuator arms 125 (one shown) inthe form of a comb that is pivotally mounted to base 113 about a pivotassembly 123. A controller 119 is also mounted to base 113 forselectively moving the comb of arms 125 relative to disks 115.

[0016] In the embodiment shown, each arm 125 has extending from it atleast one cantilevered load beams or suspensions 127, a magneticread/write transducer or head 129 mounted on a slider secured to aflexure that is flexibly mounted to each suspension 127. The read/writeheads 129 magnetically read data from and/or magnetically write data todisks 115. The level of integration called head gimbal assembly is head129 and the slider are mounted on suspension 127. Suspensions 127 have aspring-like quality which biases or urges the slider against the disk toenable the creation of the air bearing film between the slider and disksurface. A voice coil 133 housed within a conventional voice coil motormagnet assembly 134 (top pole not shown) is also mounted to arms 125opposite the head gimbal assemblies. Movement of the actuator 121(indicated by arrow 135) by controller 119 moves head gimbal assembliesradially across tracks on the disks 115 until the heads 129 settle onthe target tracks. The head gimbal assemblies operate in a conventionalmanner and always move in unison with one another, unless drive 111 usesmultiple independent actuators (not shown) wherein the arms can moveindependently of one another.

[0017] Referring now to FIGS. 1 and 2, a spacer ring 141 is securedadjacent to the central drive hub 117 of the spindle motor at the innerdiameter of disks 115 via a fastening mechanism 143, such as a clamp.Spacer ring 141 is a continuous flat annular member having a generallyrectangular cross-sectional profile and is located on or adjacent to atleast one surface of disk 115 as shown. A generally concave recess orgroove 145 circumscribes the surface of spacer ring 141 and ispreferably semi-circular in shape. Alternatively, groove 145 may beformed directly in disk 115. In addition, groove 145 is coated,sputtered, or plated, for example, with a tribological layer in order toreduce frictional contact therewith. Moreover, the entire surface ofspacer ring 141 may be coated with the tribological layer. Thetribological layer may comprise, for example, a hard coating such ascarbon.

[0018] As shown in FIG. 1 and 3, a load/unload tab 151 extends from thedistal end of actuator 121, opposite voice coil 133, beyond heads 129.Tab 151 is provided with a rib or protrusion 153 that is generallycomplementary in shape to the groove 145 in spacer ring 141. Inoperation, protrusion 153 is moved into and out of groove 145 to unloadradially inward and load radially outward, respectively, heads 129 withrespect to disks 115. Alternatively, protrusion 153 also maybe coatedwith the tribological layer previously mentioned. The tribologicallayer(s) reduce wear between the contacting parts (spacer ring 141 andgroove 145, and protrusion 153) by a factor of ten or more, therebysignificantly reducing debris generated by such contact. Thus, the heads129 on actuator 121 are loaded onto disks 115 or “unlocked” in FIGS. 1and 2, and unloaded off disks 115 and onto spacer ring 141 or “locked”in FIG. 3.

[0019] In environments wherein the disk drive 111 may experience moreextreme mechanical shock, an inertial latching feature or latch 155 maybe provided for selectively engaging actuator 121 at the locked positionto better protect the components of disk drive 111. In addition, spacerring 141 may be ferromagnetic and load/unload tab 151 may have a smallmagnet attached to it (at, for example, protrusion 153), or vice versa.This allows enhanced engagement between the two parts.

[0020] The present invention has several advantages. Although theinvention has many applications, it is particularly well suited forprotecting the heads and disks during routine and/or relatively lowmechanical shock events in low cost disk drives having one or two disksurfaces. The read/write heads are loaded and unloaded at the spacerring located at the inner diameter of the disks. The combination of thegroove in the spacer ring and the protrusion on the actuator enhance theability of the disk drive to retain the actuator arm over a simplefrictionally-retained actuator.

[0021] While the invention has been shown or described in only some ofits forms, it should be apparent to those skilled in the art that it isnot so limited, but is susceptible to various changes without departingfrom the scope of the invention.

What is claimed is:
 1. A disk drive, comprising: a housing; a spindlemotor mounted to the housing; a media storage disk mounted to thespindle motor for rotation relative to the housing, the disk having aninner diameter and an outer diameter; a recess formed in the diskadjacent to the inner diameter; and an actuator pivotally mounted to thehousing for motion relative to the disk, and having a head for readingdata from and writing data to the disk; and a tab extending from theactuator for engaging the recess when the actuator is in a lockedposition to prevent the head from loading with respect to the disk andthereby reduce damage to the head and the disk during shock events, anddisengaging the recess when the actuator is in an unlocked position suchthat the head is permitted to load with respect to the disk.
 2. The diskdrive of claim 1 wherein the recess is formed in a spacer ring at theinner diameter of the disk.
 3. The disk drive of claim 1 wherein therecess is generally concave in shape and circumscribes a surface of thedisk.
 4. The disk drive of claim 1 wherein the recess is coated with atribological layer to reduce friction during contact with the tab. 5.The disk drive of claim 4 wherein the tribological layer comprisescarbon.
 6. The disk drive of claim 1 wherein the tab extends from adistal end of the actuator beyond the head.
 7. The disk drive of claim 1wherein the tab has a protrusion that is generally complementary inshape to the recess in the disk.
 8. The disk drive of claim 1 whereinthe tab is coated with a tribological layer for reducing friction duringcontact with the recess.
 9. The disk drive of claim 1, furthercomprising a latch for engaging the actuator in the locked positionduring extreme mechanical shock.
 10. The disk drive of claim 1 whereinone of the tab and the recess is ferromagnetic, and further comprising amagnet on the other of the tab and the recess for engaging said one ofthe tab and the recess.
 11. A disk drive, comprising: a housing; aspindle motor mounted to the housing; a media storage disk mounted tothe spindle motor for rotation relative to the housing, the disk havingan inner diameter and an outer diameter; a spacer ring mounted to thespindle motor adjacent to the inner diameter of the disk; a grooveformed in and circumscribing the spacer ring; an actuator pivotallymounted to the housing for motion relative to the disk, and having ahead for reading data from and writing data to the disk; and a tabextending from a distal end of the actuator and having a protrusion forengaging the groove when the actuator is in a locked position to preventthe head from loading with respect to the disk and thereby reduce damageto the head and the disk during shock events, and disengaging the groovewhen the actuator is in an unlocked position such that the head ispermitted to load with respect to the disk.
 12. The disk drive of claim11 wherein the groove is generally semi-circular in shape and theprotrusion is generally complementary in shape to the groove.
 13. Thedisk drive of claim 11 wherein the spacer ring is coated with atribological layer to reduce friction during contact with theprotrusion.
 14. The disk drive of claim 11 wherein the tribologicallayer comprises carbon.
 15. The disk drive of claim 11 wherein theprotrusion is coated with a tribological layer for reducing frictionduring contact with the groove.
 16. The disk drive of claim 11, furthercomprising a latch for engaging the actuator in the locked positionduring extreme mechanical shock.
 17. The disk drive of claim 11 whereinthe spacer ring is ferromagnetic, and wherein the protrusion has amagnet for engaging the spacer ring.
 18. A method of reducing damage toa read/write head and a media storage disk during shock events to a diskdrive, comprising: (a) providing a disk drive with a media storage diskmounted to a spindle, a spacer ring with a groove adjacent to an innerdiameter of the disk, and an actuator with a read/write head; (b)rotating the disk and moving the actuator relative to the disk such thatthe head reads data from and writes data to the disk; and (c) moving thehead toward the inner diameter of the disk such that a tab extendingfrom the actuator engages the groove to prevent the head from loadingwith respect to the disk.
 19. The method of claim 18, further comprisingthe step of disengaging the groove with the tab such that the head ispermitted to load radially outward with respect to the disk.
 20. Themethod of claim 18, further comprising the step of coating the groovewith a tribological layer to reduce friction during contact with thetab.